Explain Definition and 1000 Threads

I thought of this today while studying relativity. Imagine a very large disc spinning with an arbitrary angular velocity. Perhaps w=57 rad/s (this is the speed of a CD, got this from a random physics text, whatever, the speed is really not important).. The speed of light is c=3*10^8 m/s...

In a nuclear reactor, the trick is to create high pressures that can turn a turbine. For that, water is boiled by the reactor. As the steam goes through the turbine, it decompresses and cools and eventually turns back into a liquid. So far so good. But the water that leaves the reactor has to be...

Anything that is massless must follow null geodesics. Why is this?

Need help finding Current on one resistor when there are 2 batteries Homework Statement Find Current in the 3 ohm resistor Sorry it didnt come out right. ill explain what it is. 12V meter on the left, + on top - on bottom. then if you go counter-clockwise you will hit a 6ohm resistor...

This is an example from the book and it is not a homework. There is one part of the step I just don't get. This is the question on page 236 of Griffiths "Introduction to Electrodynamics": Example 5.11 A spherical shell, of radius R, carrying a uniform surface charge \rho , is set spinning...

Homework Statement What is the orientation of the loop relative to the magnetic field when the current has its maximum, and its minimum magnitude. Homework Equations Ohm's law & Faraday's lawThe Attempt at a Solution The loop of wire is perpendicular to the magnetic field which gives it it's...

My question is best explained by a Gedankenexperiment. First we have a hydrogen atom, with the electron not collapsing into the nucleus for the well-known reason of its minimum energy being above that needed to overcome the Coulomb force. Fine. Now replace the proton in the nucleus with a...

http://map.gsfc.nasa.gov/media/070950/070950b.jpg So the x-axis is multipole moment, which I remember from 2nd-quarter electromagnetism. Anyways, it surprises me that 1000-order multipole moments can even be physically significant.

I never understood this how do 2 like charges stay together, the electro is it like eddy currents or something

Homework Statement I have attached my question. I don't understand how A can turn into B? (the highlighted parts) Homework Equations The Attempt at a Solution I finished the whole question, but I don't understand why arcsec turns into arctan...

I'm trying this question. i know that resistance is the concept of ohms law together with electric potential giving rise to V/I but i can't seem to know how to start. Please advice A material of resistivity r is formed into the shape of a truncated cone of altitude h. The bottom end has...

As I learn about Newton's Third Law:For every force applied to object A by another object B, there is an equal and opposite force(reaction) applied to object B by object A. I think if we had two equal and opposite forces exerts on a thing so it will not move! Also, if there is an astronaut...

Can anyone help me with this problem? I've uploaded the original problem and the way I solved it. The way they do it, as you can see, is a bit more involved. I did it a bit differently. I also came up with a bit of a different answer. I came up with 3200 N for T1 and for T2, I came up with...

Anybody here how could explain to me in the simplest terms triality? I know some very littel Lie and representation theory. As I understand there are vector and spinor representations for so(n). If n is even, there are two spin reps and one vec rep, if n is odd there is one spin rep and one...

Can someone please explain hybridization to me, the best way you can, I don't understand it at alll. Any way you can explain would be a great help. Thank You (:

So, I have to write a sestina for english class. While searching wikipedia, i came across this image I suspect this has something to do with being tired, but what does the spiral mean? I'm with it as far as the first transition (going clockwise). The sixth line does indeed become the first...

my question leads to something bigger but to start g force on Earth is 9.8m/s2 for simlicity let's say 10. 1-is it rite to say if you drop an object in the 1st sec its acceleration is 10m/s2 in the 2nd sec it's 100m/s then in the 3rd sec it's 10000 m/s 2-if the above is correct what is the...

So in this engineering course I do at my university called Statics, we often use a unit of lb per ft as a unit of force when calculating moments. However, I was just watching an episode of Big Bang Theory when Sheldon said something about a common mistake being when people use lb per ft as a...

When your dealing with the x-component in projectile motion you work with the cosine of some angle. Yet, when your working with the x-component in force you work with the sin of some angle on inclined plane. It may seem like a silly question, but it keeps confusing me on my homework problems.

My professor didn't explain this well. Question: http://i324.photobucket.com/albums/k327/ProtoGirlEXE/q1.jpg Answer: (part 1) http://i324.photobucket.com/albums/k327/ProtoGirlEXE/q2.jpg (part 2) http://i324.photobucket.com/albums/k327/ProtoGirlEXE/q3.jpg I'm completely lost on...

Homework Statement Hi everybody, this is a conceptual question about gravitational potential energy that my textbook and high school teacher seem to give incomplete answers. The problem involves two masses m_{1} and m_{2}, where m_{2} > m_{1}, which are both at a radius R from the Earth's...

Can Someone explain Why we integrate over 4\pi? What allows us to get rid of Omega?

integral of (Ldv)/(AgL+v^2) from [v0,0] I'm supposed to get (...)arctan(...) where (...) are 2 different quantities. I'm confused on how to get arctan out of this integral whenarctan = integral of (1*dv)/(1+v^2) from [0,x] Help is appreciated.

Physics Forums has had problems with LaTeX for 10 months now. I'm just wondering if someone can explain what's causing it, or at least how it's possible at all. The problem and some of my thoughts are summarized in this quote:

Homework Statement Hi physics forums, thanks for responding if you do :cool: Use Ohm's law and Kirchhoff's current law to determine the current I1 in the circuit of Figure-- The Attempt at a Solution So I'm trying to fully understand what is going on here.. Besides not getting where...

Homework Statement (4 marks) Instruments that measure the force of the Earth's gravity with great accuracy are carried in airplanes over mineral-bearing landscapes. Explain how readings on the instruments indicate when there is a deposit of minerals or oil below the plane. Homework...

I'm trying to explain some physics principles to a general audience and have a few related questions: 1) What's the name of the principle that distinguishes between randomly arranged particles in an iron bar and those arranged so as to magnetize it? Is it 'coherence' or something else? 2)...

Homework Statement So I get to Abel's Theorem and I'm like, "What the fork? I think I've seen this before." Homework Equations THEOREM III. Suppose that the series ∑anxn has a positive or infinite radius of convergence R. Let 0 < r < R. Then the series converges uniformly on the closed...

How do I explain it?? Potential difference in the system discussed is independent Hi folks, - please view the attached image - my colleague and I had a major disagreement in the office. We both mutually put a lid on the discussion as we both felt that we needed more information in order to...

In general terms, but not too general.

Homework Statement A soccer coach organizing a field trip finds that 50 students have signed up. However, the bus has only 47 seats, so a few students will have to travel by car. The coach and one other coach must go on the bus. Explain two different methods for using combinations to find...

I am aware that the human body has electrical properties, But was baffled by what I witnessed Christmas Eve. I had a malfunctioning electric candle in the window. I picked it up to check the tightness of the bulb, and it immediately came on. I set it down and it went off. Three times this...

I am trying to understand everything about general relativity. I know that they have to do with how the Riemann curvature tensor uses parallel transporting a vector around a closed path. I really just don't understand the mathematics behind it. Thank you. I prefer layman's terms.

Do planets follow the curvature of spacetime as they orbit, or what is their path considered to be?

my minor in Math isn't "official", don't know how to explain it on resume I took all the required classes needed to obtain a minor in Math from my graduating school, but unfortunately more than half the classes were transfer credits from my first school I transferred out of after my first year...

Homework Statement Okay I just need someone to explain to me 2 things in the solution to a problem. Here is a link to the solution manual for the book I am using for my University Physics 1 course. http://oak.cats.ohiou.edu/~tt106402/work/phys252/Physics%20Notes/ch10.pdf if you search (crtl...

I know one way is using hoptial's law but that will be a long way. \lim _{x \rightarrow 0 } {\frac {\cos \left( \sin \left( x \right) \right) -\cos \left( x \right) }{{x}^{4}}} thanks

Homework Statement Two trains start at the same time from stations A and B (6km apart ) respectively in opposite tracks. train A accelerates uniformly at the rate of 0.5 meter per second square until it reaches a speed of 54 kmph, while train B accelerates uniformly at the rate of 0.6 meter...

http://www.tpub.com/content/engine/14105/css/14105_20.htm This website tells me that Specific Gravity is weight of substance/weight of equal volume of water or density of substance/density of water. Can someone explain how this is true? Density and weight are two different things so...

ln(-2) = ln(2) + (1+2k)*pi*i and ln(16) = ln (16) + 2m*pi*i I picked this equation from here: https://www.physicsforums.com/showthread.php?t=184129 Post #5 (D H's post. Thanks a lot!

http://tinypic.com/a/2im4z/3" If you have not been bitten with a life long love of two wheel rapid transit systems then this thread is not for you... Some additions/replacements to the "Work in Progress..." The top two left images, thrust/hp/torque, the top two right images are of a...

Homework Statement

If let's say we have the following expression √(x^2 - y^2) If I wanted to factor out x, then why can't I just take x out because a square root of a square is the base. x√(1 - y^2) But it turns out that the answer to this is incorrect and the answer to factoring out x is. x√(1 -...

Hey everyone I just started an engineering course and have been given a few questions but I am struggling with this one as i feel that i have not included all the info that should be there. Can someone tell me briefly what they would explain the term permittivity as and how they think it would...

Can someone explain to me the R formula?(expressing \displaystyle a cos \theta + b sin \theta in terms of R sin(\theta + \alpha) ) I don't really understand my textbook at all which jumped straight to the questions. Could someone please enlighten me on the logic behind this concept and how...

Can anyone explain how to draw a leading edge circle of an aerofoil. Where is the center and what is the radius of the leading edge circle

http://www.nasa.gov/images/content/498884main_DF3_Fermi_bubble_art_labels.jpg http://www.nasa.gov/mission_pages/GLAST/news/new-structure.html Could these structures account for the dark matter, or is the density profile inconsistent with two big blobs of matter/energy on both sides of the...

Please explain this paragraph from "The Selfish Gene" edit: I just noticed that I misspelled 'Selfish' in the title. However I have no idea how to edit the title after posting so kindly ignore the mistake. I have been reading "The Selfish Gene" by Richard Dawkins and all the while he looks...

Homework Statement As the title says. Homework Equations mentioned in solution The Attempt at a Solution Let Sn = {(1+1)/(1+2) , (1+2)/(1+4), (1+3)/(1+6), ...}. If ∑(1+n)/(1+2n) is convergent, then lim n-->∞ Sn = 0; to put it another way, there exists an N so that whenever n ≤...

I've taken basic college physics and chemistry courses where I learned about entropy and thermodynamics, and I can tell you that I don't know that much :) That's my background. I understand that entropy is a description of 'randomness' and possible 'states'. When I wash my hands with soap...